Portable cutting tool

ABSTRACT

The engine unit of a portable chain saw has the saw chain bar removed and replaced by an arm of an X-cross-sectional configuration and which arm is slidably and detachably connected at one end to said engine unit so that either side of said arm can be attached to said engine unit and at the other positioned in end of said arm is journaled a cutting disc positioned in the middle plane of the engine unit or to one side of the engine unit depending on which side of said arm is attached to the engine unit and a U-shaped handle is rotatably and detachably connected to said arm free end by either leg of said handle.

United States Patent 659,235 10/1900 Jeffery 32 44, 43: Sl/(lnquired): 125/(lnquired): 83/(lnquired)74/6l1:30/(1nquired):51/170241 References Cited UNITED STATES PATENTS 3,073,073 1/1963 Van Pelt .1 143/32 3,073,193 l/1963 Grant 143/32X 3,266,534 8/1966 Camesecca et a1 143/32 FOREIGN PATENTS 1,483,481 4/1967 France 143/32( 14) 387,922 2/1965 Switzerland 143/32( 14) Primary Examiner-Donald R. Schran Attorney-Linton 8L Linton ABSTRACT: The engine unit of a portable chain saw has the saw chain bar removed and replaced by an arm of an X-crosssectional configuration and which arm is slidably and detachably connected at one end to said engine unit so that either side of said arm can be attached to said engine unit and at the other positioned in end of said arm is journaled a cutting disc positioned in the middle plane of the engine unit or to one side of the engine unit depending on which side of said arm is attached to the engine unit and a U-shaped handle is rotatably and detachably connected to said arm free end by either leg of said handle.

PATENTEB JUN sum SHEET 1 OF 2 INVENTOR GUNTHER H. w mega/27w ATTORNEYS PATENTEU JUN 8mm 3,583,106

SHEET 2 OF 2 INVENTOR GUNTHER W. WDOBBERTl/V ATTORNEYS PORTABLE CUTTING TOOL The present invention relates to portable cutting tools of the kind comprising an engine unit, an arm adapted to be detachably secured with one end portion to one side of said engine unit in a position projecting from the engine unit, said arm being provided at its opposite end with journaling means for a cutter disc driven from the engine shaft by means of a transmission belt or the like, said cutting disc being disposed to that side of said arm which faces that longitudinal middle plane of said engine unit which is parallel with the plane of the cutting disc.

Cutting tools of this kind are previously known, e.g. from US. Pat. No. 3,383,578 of May 14, 1968. In order to obtain a good balance when using such tools, the tools have been made with the cutting disc placed in or close to the longitudinal line of gravity of the tool. This means, however, that the engine unit will project outside the plane of the cutting disc on both sides thereof which prevents cutting work close to a wall or the like. It has been proposed to overcome this inconvenience by making the cutting disc shaft with attachment means for the cutting disc at both ends. Such an embodiment, however, involves considerable complications and increased production costs.

The object of the invention is to provide a cutting tool of the kind set forth above which makes it possible to rapidly and conveniently readjust the position of the cutting disc with respect to the engine unit. According to the invention, that end portion of the arm which is to be secured to the engine unit and the means for securing the arm to the engine unit are made in such a manner that the arm may be mounted on the engine unit also in a position wherein the arm has been rotated 180 around its longitudinal axis from the first-mentioned position, thereby placing the cutting disc on the opposite side of the arm, whereas the belt pulley or the like included in the belt transmission and provided at the free end of the arm will be disposed in the same plane as in the first mentioned position of the arm. With a cutting tool according to the invention it will only be necessary to detach the arm carrying the cutting disc from the engine unit and to mount the arm in the turned around position in order to get the cutting disc placed in such a manner that the tool may be used close to a wall or the like.

One embodiment of the invention will be described more closely herebelow with reference to the accompanying drawings, wherein,

FIG. I is a side view ofa cutting tool according to the invention,

FIG. 2 is a partly broken view from above with the cutting disc in one working position,

FIG. 3 is a view from above with the cutting disc in the other working position, and.

FIG. 4 is a cross section through the arm carrying the cutting disc taken on the line lV-IV in FIG. 1.

In the embodiment shown in the drawings the engine unit which as a whole is indicated with the reference numeral 1 is constituted by the engine unit for a portable chain saw, the saw chain bar of which has been removed and replaced by an arm 2 which has one end secured to the engine unit in a position projecting out from the engine unit and which is provided at its free end with a journal for the shaft of a rotary cutting disc 3. As appears from FIG. 2, there is provided a transmission belt for driving the cutting disc 3 from the engine shaft 4. The transmission belt includes a belt pulley 5 on the engine shaft, a belt pulley 6 on the cutting disc shaft and a belt 7. For handling the tool there is provided a handle 8 at the rear of the engine unit and there is also provided a carrying handle 9 at the front end of the arm 2.

As will appear from FIG. 4, the arm 2 is made with a substantially X-shaped cross section. The flanges 10, 11, 12 and 13 of the arm which form the legs of this cross section form two channels at opposite sides of the arm for receiving the two runs of the driving belt 7. In FIG. 4, numeral 14 indicates the attachment plate on the engine unit to the flat outer side of which the saw bar of the chain saw is normally intended to be mounted. Stud bolts 15 and corresponding nuts are provided for securing the saw bar or the cutting disc arm, respectively, to the engine unit. In the embodiment shown, an intermediate plate 16 is provided for the mounting of the cutting disc arm 2 to the engine unit. The plate 16 has a flat surface on one side for being placed against the attachment portion 14 of the engine unit, and at the opposite side, the plate 16 is formed with surfaces corresponding to the side surfaces of the arm 2. In the present embodiment the plate 16 is made in one piece with a transmission guard 17, but the plate 116 may of course also be made as a separate part.

With further reference to FIG. 4, the arm 2 is shaped in such a way, at least at the attachment end, that it may be mounted to the engine unit in a position in which the arm has been rotated around its longitudinal axis from the position shown in FIG. 4. In the embodiment shown, the arm, or at least the portion thereof including the attachment end, is made symmetrical with respect to the vertical and horizontal longitudinal middle planes according to FIG. 4 so that in said turned around position of the arm the flanges I1 and 12 will be lying against the plate 16 in the same manner as the flanges l0 and 13in the position shown in FIG. 4. This makes it possible to mount the arm so that the cutting disc will be positioned either as illustrated in FIG. 2 or as illustrated in FIG. 3.

The handle 9 comprises a stem portion 18 bent at approximately right angles to the handle portion and secured to that side of the arm 2 which is opposite to the cutting disc by means of a bracket 19. The bracket may be loosened so that the handle may be detached and reinserted with the stern portion 18 from the opposite side of the bracket which may thereafter be tightened anew so that the handle 9 also, in the position of the arm 2 illustrated in FIG. 3, will be positioned above the cutting disc. Further, the handle 9 is rotatable by means of its stem portion 18 relative to the bracket 19 so that the handle may be adjusted to, for instance, the position illustrated in broken lines in FIG. 3. In the embodiment shown, the handle 9 is constituted by the middle portion of a yoke, one leg of which forms the stern portion 18 and the other leg 21 of which may also be used as a handle. The cutting disc guard 20 is adjustable around the cutting disc shaft for instance in the manner disclosed in Swedish Pat. Specification 212948, so that the guard may be rotated approximately 180 when the mounting of the arm 2 to the engine unit is reversed.

As shown in FIG. 4 the flanges 10, Ill, 12 and 13 of the arm 2 are formed at their free edges with beads 22 adapted to cooperate with bent-around edge portions of guard rails 23 and 24 which are adapted to be pushed on to the flanges 10, I1 and 12, 13, respectively, for covering the channels for the two runs of the drive belt. In the embodiment shown, the rails 23 and 24 are formed by the legs of an elongated yoke, the middle portion 25, see FIGS. 1 and 3, of which cover the transmission belt at the free end of the arm 3. The yoke 23, 24 and 25 may be pushed on to the arm 2 from the free end thereof.

As will appear from FIG. 1, the arm 2 is provided at the end intended to be connected with the engine unit with a slot 26 extending in the longitudinal direction of the arm for receiving the bolts 15. This slot is open towards the rear end of the arm. When the arm 2 is reversed in order to reposition the cutting disc e.g. from the position shown in FIG. 2 to the position shown in FIG. 3, the nuts on the bolts 15 are loosened and the arm displaced backwardly, that is, towards to engine unit so far that the drive belt 7 be removed from the pulley 6 after the belt guard 23-25 has been removed. Thereafter, the arm is pushed forwardly, i.e. away from the engine unit, turned 180 around its longitudinal axis and pushed into engagement with the studs 15, whereafter the drive belt is replaced. The nuts of the bolts 15 are then tightened after the position of the arm 2 in the longitudinal direction has been adjusted for obtaining sufiicient tension in the belt 7.

The invention is not limited to the embodiment described hereinbefore and shown in the drawings which is an example only and said embodiment is susceptible of modifications with respect to its details within the scope of the appended claims. For instance, the transmission belt may be replaced by a chain transmission.

lclaim:

l. A portable cutting tool comprising the engine unit of a portable chain saw with the saw chain bar detached and which engine unit is provided with a driving shaft, a side flat surface adjacent to and extending at right angles to the axis of said shaft and bolts extending from said flat surface, an arm having a symmetric X-shaped cross section providing a pair of channels and V-shaped sides at one end portion of said arm, said arm one end portion having an opening for detachably receiving said bolts therethrough with said arm extending from the side of the engine unit having said flat surface, a plate having an opening for receiving said bolts therethrough, a flat contact surface mounted on said engine unit flat surface and a V- shaped surface having one of said arm V-shaped sides positioned thereon with said plate between said engine unit and said arm, journaling means carried by the opposite end of said arm, a cutting disc rotatably mounted on said journaling means and positioned on one side of said arm, a pulley connected to said cutting disc and rotatably mounted on said journaling means at said opposite end of said arm, a pulley connected to said drive shaft, a transmission belt extending around said pulleys for driving said cutting disc and through said arm channels and said arm being capable of having either of its V-shaped sides positioned on said plate V-shaped surface whereby said cutting disc can be positioned towards the middle plane of said engine unit or by rotating said arm around its longitudinal axis, can be positioned to one side of said engine unit.

2. A cutting tool as claimed in claim 1 wherein said plate is of one piece with a belt guard arranged at the end of said transmission belt disposed adjacent said engine unit.

3. A cutting tool as claimed in claim 1 including a U-shaped handle with two stem portions and a handle portion and a bracket mounted on said arm opposite end with either of said stem portions therein with said handle portion extending at right angles to the longitudinal direction of said arm and to the plane of said cutting disc.

4. A cutting tool as claimed in claim 3 wherein said handle is provided at an angle to said stem portions and the stem portion in said bracket being rotatable around the longitudinal axis of said stem portion.

5. A cutting tool as claimed in claim 1 wherein said arm has free edges on both sides of said arm channels, beads are provided on said arm free edges and an elongated yoke having parallel legs and a curved middle portion, has bent-around edge portions on said legs slideably engaging said beads whereby said yoke covers said channels and the part of the transmission belt at the opposite end of said arm. 

1. A portable cutting tool comprising the engine unit of a portable chain saw with the saw chain bar detached and which engine unit is provided with a driving shaft, a side flat surface adjacent to and extending at right angles to the axis of said shaft and bolts extending from said flat surface, an arm having a symmetric X-shaped cross section providing a pair of channels and V-shaped sides at one end portion of said arm, said arm one end portion having an opening for detachably receiving said bolts therethrough with said arm extending from the side of the engine unit having said flat surface, a plate having an opening for receiving said bolts therethrough, a flat contact surface mounted on said engine unit flat surface and a V-shaped surface having one of said arm V-shaped sides positioned thereon with said plate between said engine unit and said arm, journaling means carried by the opposite end of said arm, a cutting disc rotatably mounted on said journaling means and positioned on one side of said arm, a pulley connected to said cutting disc and rotatably mounted on said journaling means at said opposite end of said arm, a pulley connected to said drive shaft, a transmission belt extending around said pulleys for driving said cutting disc and through said arm channels and said arm being capable of having either of its V-shaped sides positioned on said plate V-shaped surface whereby said cutting disc can be positioned towards the middle plane of said engine unit or by rotating said arm 180* around its longitudinal axis, can be positioned to one side of said engine unit.
 2. A cutting tool as claimed in claim 1 wherein said plate is of one piece with a belt guard arranged at the end of said transmission belt disposed adjacent said engine unit.
 3. A cutting tool as claimed in claim 1 including a U-shaped handle with two stem portions and a handle portion and a bracket mounted on said arm opposite end with either of said stem portions therein with said handle portion extending at right angles to the longitudinal dirEction of said arm and to the plane of said cutting disc.
 4. A cutting tool as claimed in claim 3 wherein said handle is provided at an angle to said stem portions and the stem portion in said bracket being rotatable around the longitudinal axis of said stem portion.
 5. A cutting tool as claimed in claim 1 wherein said arm has free edges on both sides of said arm channels, beads are provided on said arm free edges and an elongated yoke having parallel legs and a curved middle portion, has bent-around edge portions on said legs slideably engaging said beads whereby said yoke covers said channels and the part of the transmission belt at the opposite end of said arm. 